Brominated indigo sulfid and process of making same.



' examp UNITED STATES PA ENT OFFICE.

'EMIL KRAUS, OF FRAN KFORTONTHEIV1AIN, GERMANY, ASSIGNOR TO CASSELLA COLOR COMPANY, OF NEW YORK, N. Y. 4

BROMINATED INDIGO SULFID AND PROCESS OF MAKING SAME.

Specification of Letters Patent.

Patented May 4, 1909.

. Application filed February 13, 1909. Serial No. 477,727.

able diluting agent, such as for instance nitrobenzol, chlorbenzol, etc. to temperatures exceeding 160 (3., is transformed into indigo sulfids, whlch are technically important especially in the form of their halogen derivatives. Of particular importance are the roducts which are obtained by the simu taneous reaction of bromin and sulfur on indi o. According to the analytiral result, they contain one atom of sulfur on two molecules of indigo, the contents of bromin varying with the quantity of bromin employed. The resulting dyestufi's may be vat-dyed quite well, and dyelngs so obtained,

are distinguished by a considerably purer shade, and better fastness to washing and chloring, when compared with indigo. Compared'with the bromindi o dervatives, they ,are of' a more greenish sl rade, and particularly of a superior fastness to light.

'lhe )roccss is illustrated by the following fc: kilos indigo are sus )ended in 5(lkilos nitrobenzol, to which is ad ed, under constant stirring in the cold, the solution of 32 kilos bromin and kilos nitrobenzol. 1.8 kilos sublimed sulfur are then added, and the whole is allowed to stand for about 12 hou'rs at ordinary temperature. It is then.

- heated gradually to 120 C., while stirring,

this temperature maintained for about 4 hours, after which it is raised to 180 (3., and

the melt stirred at 180-20U 0., until the formation of hydrobromic acid has ceased (which will be in about 1'1, hours). The dyestuifis then filtered oil, washed with henzol or alcohol, or the nitro-benzol is distilled oil, to best advantage in a vacuum.

The new dyestuli' forms a darlg blue powder almost insoluble in alcohol, benzol, chloroform; soluble in boiling nitrobenzol and naplrtlnrlenc with a greenish-blue color, in concentrated sulfuric acid with a bluish green, in oleum of 20% with a sky-blue color. It dissolves by means of hydrosuliitcs, form in .a yellow vat from which cotton is dyed clear, blue shades. According to the analysis it corresponds to the formula of a triinomin-indigo suliid [C H N O BrQ S].

Having now particularly described and ascertained the nature of my said invention and in what manner the same .18 to be performed I declare that what I claim is 1- 1. The )rocess of producing brominated indigo sulfids by heating indigo in-the presence of suitable diluting agents with sulfur and bromin substantially as described,

2. The brominated indigo sulfid, which is a dark blue powder almost insoluble in alco hol, bcnzol, chloroform, soluble in boiling nitrob'enzol and naphthalene with a greenish-blue color, in a concentrated sulfuric acid with a bluish-green, in oleum of 20% with a sky-blue color, dissolving by means of hydrosulfites, forming a yellow vat from which cotton is (lyedclear, blue shades, substantially as described.

In witness whereof I have hereunto signed my name this 29th da of January, 1909, in the presence of two su scribing witnesses.

EMIL KRAUS. 

